Merged from MOODLE_15_STABLE

Curiosly, the bug is in 1.4 and HEAD, but no in 1.5... Uhmmm,
be careful with those merges... ;-)

(http://moodle.org/bugs/bug.php?op=show&bugid=4014)

Fixed a serious bug in table_column() that modified column not having NOT NULL for postgres (merged from 15_STABLE)

We have extremely crappy support for postgres7 in those modules in 14_STABLE, someone forgot to backport from HEAD?

Fixed a problem that courses cannot be move to another category when there are quotes in some text fields.

(http://moodle.org/bugs/bug.php?op=show&bugid=3293)

(http://moodle.org/bugs/bug.php?op=show&bugid=3291)

Merging fix for bug 2635 from HEAD.

populated (because we were working against the same $tmpunit
always).

(plus a bit of change in coding style...)

Credits go to Julian Sedding!

SQL errors are now (optionally -- defaults to off) logged to the apache error log. Helps debugging! Credit: Patrick Li <patrick@catalyst.net.nz>

Default course id for htmlarea insert image to 0 rather than empty string to prevent invalid sql. Credit: Patrick Li

(http://moodle.org/bugs/bug.php?op=show&bugid=2702)